1. Field of the Invention
The invention relates in general to a thin film transistor substrate, a display apparatus using the same and a manufacturing method thereof, and more particularly to a thin film transistor substrate with a composite plate, a display apparatus using the same and a manufacturing method thereof.
2. Description of the Related Art
As the application of display apparatus is getting more and more popular, the research and development in the elements has become one of the prominent tasks for manufacturers. Originally, most display apparatus adopts glass substrate due to its excellent performance in transparency, surface flatness, water/oxygen resistance and dimension stability (that is, low coefficient of thermal expansion). However, glass substrate is not suitable for flexible or impact resistant display apparatus for its poor strength, fragility and poor flexibility. Currently, some display apparatus replace glass substrate with plastic substrate to achieve better performance in toughness, strength, specific weight and flexibility.
However, plastic substrate cannot achieve the same performance with glass substrate in temperature resistance, chemical resistance, water/oxygen resistance and dimension stability. Particularly, the performance of plastic substrate requires low-temperature or other specific manufacturing ways for passing existing manufacturing specifications. Besides, since water and oxygen are critical to stability and lifespan of electronic elements, poor water/oxygen resistance makes the properties of the product hard to maintain. In addition, the plastic substrate has poor rigidity, the bending level of the plastic substrate hard to meet the operation specifications of existing manufacturing machines even when the thickness is close to glass substrate. Therefore, the plastic substrate must be combined with a rigidity carrier in process. After process finished, the rigidity carrier and the plastic substrate need to be separated, incurring additional materials and costs.
Some manufacturers try to replace glass substrate with metal foil to provide excellent performance in terms of rigidity, strength, toughness, flexibility, temperature resistance, chemical resistance, water/oxygen resistance and dimension stability. However, metal having large specific weight, metal plate cannot meet the lightweight requirement of display. In order to reduce the weight, after process finished, thin film transistors are covered by a protection layer and the bottom surface of metal plate is etched and thinned to obtain a metal foil. Thus, using metal foil incurs high cost and transistors may be damaged during the etching/thinning process. Thus, find some material to replace glass substrate has become a prominent task for the industries.